Brodi Willardposted a picture that's been shared tens of thousands of times, saying hives on her son's arm lead to an influenza diagnosis!

Willard said her son came home from school with the rash.

"We tried changing his clothes and giving him a bath, but nothing helped," she explained in her post. "I called his pediatrician. They said they had two kids come into the office that day with the same symptoms and tested positive for influenza. I took him to the doctor this morning, and he tested positive for Influenza B."

Oscar Alea, MD, a pediatric pulmonologist, says the flu presents differently in different people, and in some cases you could get a rash.

"That's one of the manifestations of influenza," he explained, "It can present with different types of rashes. Some of them may appear to be hives, but most appear to be raised lesions that are red. It can be generalized, and sometimes it appears more isolated to the upper body."

He says in most cases, however, rashes will appear along with other symptoms.

"Influenza can mimic a lot of different infections," he said, "but typically you need quite a few different symptoms to think it's influenza."

Even a rash by itself is cause for concern if it doesn't clear up. A lot of things can present with a rash including Shingles, Meningococcal disease, even Lyme disease.

"You should see your primary care provider if its a skin manifestation that continues to linger and not resolve," Alea said.